Low temperature gas-phase carbon removal

ABSTRACT

A method of etching carbon films on patterned heterogeneous structures is described and includes a gas phase etch using remote plasma excitation. The remote plasma excites a fluorine-containing precursor and an oxygen-containing precursor, the plasma effluents created are flowed into a substrate processing region. The plasma effluents etch the carbon film more rapidly than silicon, silicon nitride, silicon carbide, silicon carbon nitride and silicon oxide.

FIELD

Embodiments of the invention relate to selectively removing carbonhardmask material.

BACKGROUND

Integrated circuits are made possible by processes which produceintricately patterned material layers on substrate surfaces. Producingpatterned material on a substrate requires controlled methods forremoval of exposed material. Chemical etching is used for a variety ofpurposes including transferring a pattern in photoresist into underlyinglayers, thinning layers or thinning lateral dimensions of featuresalready present on the surface. Often it is desirable to have an etchprocess which removes one material faster than another helping e.g. apattern transfer process proceed. Such an etch process is said to beselective of the first material relative to the second material. As aresult of the diversity of materials, circuits and processes, etchprocesses have been developed with a selectivity towards a variety ofmaterials.

Dry etch processes are often desirable for selectively removing materialfrom semiconductor substrates. The desirability stems from the abilityto gently remove material from miniature structures with minimalphysical disturbance. Dry etch processes also allow the etch rate to bemore abruptly stopped by removing the gas phase reagents. Some dry-etchprocesses involve the exposure of a substrate to remote plasmaby-products formed from one or more precursors. For example, remoteplasma excitation of ammonia and nitrogen trifluoride enables siliconoxide to be selectively removed from a patterned substrate when theplasma effluents are flowed into the substrate processing region. Dryetch processes are needed to selectively remove carbon films such ascarbon hardmasks from patterned substrates.

SUMMARY

A method of etching carbon films on patterned heterogeneous structuresis described and includes a gas phase etch using remote plasmaexcitation. The remote plasma excites a fluorine-containing precursorand an oxygen-containing precursor, the plasma effluents created areflowed into a substrate processing region. The plasma effluents etch thecarbon film more rapidly than silicon, silicon nitride, silicon carbide,silicon carbon nitride and silicon oxide.

Embodiments of the invention include methods of etching a patternedsubstrate. The methods include transferring the patterned substrate intoa substrate processing region of a substrate processing chamber. Thepatterned substrate has exposed portions of carbon-containing materialand an exposed alternative material. The methods further include flowingan oxygen-containing precursor into a remote plasma region fluidlycoupled to the substrate processing region. The methods further includeflowing a fluorine-containing precursor into the remote plasma region.The methods further include combining the oxygen-containing precursorwith the fluorine-containing precursor. The methods further includeforming a remote plasma in the remote plasma region from theoxygen-containing precursor and the fluorine-containing precursor toproduce plasma effluents. The methods further include passing the plasmaeffluents through an ion suppressor and subsequently into the substrateprocessing region. The methods further include etching the exposedportions of carbon-containing material.

Embodiments of the invention include methods of etching a patternedsubstrate. The methods include transferring the patterned substrate intoa substrate processing region of a substrate processing chamber. Thepatterned substrate has exposed carbon hardmask. The methods furtherinclude flowing a fluorine-containing precursor and an oxygen-containingprecursor into a remote plasma region fluidly coupled to the substrateprocessing region while forming a remote plasma in the remote plasmaregion to produce plasma effluents. The methods further include flowingthe plasma effluents in the substrate processing region and etching theexposed carbon hardmask.

Embodiments of the invention include methods of etching a patternedsubstrate. The methods include transferring the patterned substrate intoa substrate processing region of a substrate processing chamber. Thepatterned substrate has exposed portions of carbon hardmask. The methodsfurther include flowing nitrogen trifluoride into a remote plasma regionand combining oxygen with the nitrogen trifluoride. The remote plasmaregion is fluidly coupled to the substrate processing region. Themethods further include forming a remote plasma from the nitrogentrifluoride and the oxygen in the remote plasma region to produce plasmaeffluents. The methods further include passing the plasma effluentsthrough a showerhead disposed between the remote plasma region and thesubstrate processing region. The methods further include etching theexposed portions of carbon hardmask and removing the patterned substratefrom the substrate processing region.

Additional embodiments and features are set forth in part in thedescription that follows, and in part will become apparent to thoseskilled in the art upon examination of the specification or may belearned by the practice of the disclosed embodiments. The features andadvantages of the disclosed embodiments may be realized and attained bymeans of the instrumentalities, combinations, and methods described inthe specification.

DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the disclosedtechnology may be realized by reference to the remaining portions of thespecification and the drawings.

FIG. 1 shows a method of selectively etching a carbon-containing filmaccording to embodiments of the invention.

FIG. 2 shows a method of selectively etching a carbon hardmask accordingto embodiments of the invention.

FIG. 3 shows a top plan view of one embodiment of an exemplaryprocessing tool according to embodiments of the invention.

FIGS. 4A and 4B show cross-sectional views of an exemplary processingchamber according to embodiments of the invention.

FIG. 5 shows a schematic view of an exemplary showerhead configurationaccording to embodiments of the invention.

In the appended figures, similar components and/or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If only the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

DETAILED DESCRIPTION

A method of etching carbon films on patterned heterogeneous structuresis described and includes a gas phase etch using remote plasmaexcitation. The remote plasma excites a fluorine-containing precursorand an oxygen-containing precursor, the plasma effluents created areflowed into a substrate processing region. The plasma effluents etch thecarbon film more rapidly than silicon, silicon nitride, silicon carbide,silicon carbon nitride and silicon oxide.

In order to better understand and appreciate the invention, reference isnow made to FIG. 1 which is a flow chart of a method of selectivelyetching a carbon-containing film 100 according to embodiments. Prior tothe first operation, a structure is formed in a patterned substrate. Thestructure possesses exposed portions of a carbon-containing film. Thesubstrate is then delivered into a substrate processing region inoperation 110.

Nitrogen trifluoride is flowed into a remote plasma region and excitedin a plasma (operation 120). The remote plasma region may be outside orinside the substrate processing chamber in embodiments. Anoxygen-containing precursor, O₂, is concurrently flowed into the remoteplasma region, according to embodiments, to be excited along with thefluorine-containing precursor (also operation 120). In general, afluorine-containing precursor is flowed into the remote plasma regionand the fluorine-containing precursor comprises at least one precursorselected from the group consisting of atomic fluorine, diatomicfluorine, nitrogen trifluoride, carbon tetrafluoride, hydrogen fluorideand xenon difluoride. The oxygen-containing precursor may more generallyinclude one or more of oxygen, ozone, nitrogen dioxide and nitrousoxide. The oxygen-containing precursor may be supplied along with thenitrogen trifluoride or through a separate supply pathway into theremote plasma region in embodiments. The separate plasma region may bereferred to as a remote plasma region herein and may be within adistinct module from the processing chamber or a compartment within theprocessing chamber. Plasma effluents are formed from theoxygen-containing precursor and the nitrogen trifluoride in the plasmaand the plasma effluents are flowed from the remote plasma region intothe substrate processing region in operation 130.

The patterned substrate temperature is maintained at about 15° C.(operation 140) during the selective removal of material. The patternedsubstrate is selectively etched (operation 150) such thatcarbon-containing material from the exposed portions of thecarbon-containing film is selectively removed at a higher rate thanother exposed materials. The precursor combinations described hereinhave been found to produce reactants which etch only carbon-containingmaterial, in embodiments. Silicon, silicon nitride and silicon oxide maynot etch using these chemistries and so portions of exposed silicon,silicon nitride, silicon carbide, silicon carbon nitride or siliconoxide are also present on the patterned substrate according toembodiments. Process effluents and unreacted reactants are removed fromthe substrate processing region and then the substrate is removed fromthe processing region (operation 160).

The etch processes introduced herein have been found to providecarbon-containing material selectivity not only to high density siliconfilms but also to low density silicon films. The broad silicon oxideselectivity enables these gas phase etches to be used in a broader rangeof process sequences. Exemplary deposition techniques which result inlow density silicon films include chemical vapor deposition usingdichlorosilane as a deposition precursor, spin-on glass (SOG) orplasma-enhanced chemical vapor deposition. High density silicon filmsmay be deposited as thermal oxide (exposing silicon to, e.g., O₂ at hightemperature), disilane precursor furnace oxidation or high-densityplasma chemical vapor deposition according to embodiments.

The etch process parameters described herein apply to all embodimentsdisclosed herein, including the embodiments described in FIG. 2 below.The fluorine-containing precursor and/or the oxygen-containing precursormay further include one or more relatively inert gases (e.g. He, N₂,Ar). Flow rates and ratios of the different gases may be used to controletch rates and etch selectivity. In an embodiment, thefluorine-containing gas includes NF₃ at a flow rate of between about 5sccm (standard cubic centimeters per minute) and 300 sccm, O₂ at a flowrate of between about 25 sccm and 700 sccm and He at a flow rate ofbetween about 0 sccm and 3000 sccm. Argon may be included, especiallywhen initially striking a plasma, to facilitate the initiation of theplasma. One of ordinary skill in the art would recognize that othergases and/or flows may be used depending on a number of factorsincluding processing chamber configuration, substrate size, geometry andlayout of features being etched.

Reference is now made to FIG. 2 which is a flow chart of a method ofselectively etching a carbon hardmask 200 according to embodiments.Prior to the first operation, a structure is formed in a patternedsubstrate. The structure possesses exposed portions of carbon hardmask.The patterned substrate is then delivered into a substrate processingregion in operation 210.

Nitrogen trifluoride is flowed into a remote plasma region and excitedin a plasma (operation 220). The remote plasma region may be outside orinside the substrate processing chamber, in embodiments, but is at leastseparated from the substrate processing region by a showerhead. Thefluorine-containing precursor may be the same embodiments describedearlier. An oxygen-containing precursor, nitrous oxide, is concurrentlyflowed into the remote plasma region, according to embodiments, to beexcited along with the fluorine-containing precursor. Theoxygen-containing precursor may more generally include one or more ofoxygen, ozone, nitrogen dioxide and nitrous oxide. The oxygen-containingprecursor may be supplied along with the nitrogen trifluoride or througha separate supply pathway into the remote plasma region in embodiments.Plasma effluents are formed from the oxygen-containing precursor and thenitrogen trifluoride in the plasma and the plasma effluents are flowedfrom the remote plasma region into the substrate processing region inoperation 230.

The patterned substrate temperature is maintained at about 15° C.(operation 240) during the selective removal of material. The patternedsubstrate is selectively etched (operation 250) such that exposed carbonhardmask material is selectively removed at a higher rate than anyexposed silicon, silicon nitride or silicon oxide. Portions of exposedsilicon oxide, silicon nitride, silicon carbide, silicon carbon nitrideor silicon may also be present on the patterned substrate and may alsobe essentially unetched during operation 250. The reactive chemicalspecies are removed from the substrate processing region and then thepatterned substrate is removed from the substrate processing region(operation 260).

The temperature of the patterned substrate during all etch processes(e.g. during selective removal operations 150 and 250) described hereinmay be between about −20° C. and about 140° C. in disclosed embodiments.The temperature of the patterned substrate may be between about −10° C.and about 50° C. between about −5° C. and about 40° or between about 0°C. and about 30° C. in embodiments. These patterned substratetemperature embodiments are used for both carbon-containing etch process100 and carbon hardmask etch process 200.

The pressure in the remote plasma region and/or the substrate processingregion during all etch processes (e.g. during selective removaloperations 150 and 250) may be between about 0.01 Torr and about 30Torr, between about 0.1 Torr and about 15 Torr, or between about 1 Torrand about 5 Torr in embodiments. The remote plasma region is disposedremote from the substrate processing region. The remote plasma region isfluidly coupled to the substrate processing region and both regions maybe at roughly the same pressure during processing.

Generally speaking, the films selectively etched during all etchprocesses described herein may be carbon-containing films. Thecarbon-containing films may be silicon-free, oxygen-free and/ornitrogen-free according to embodiments. The carbon-containing films maycomprise or consist of carbon and hydrogen in embodiments. Thecarbon-containing films may comprise or consist of carbon according toembodiments. The carbon-containing films may be amorphous and may beused as a masking material during the production of patternedsubstrates.

The carbon-containing film (e.g. carbon hardmask) may comprise carbon orcomprise carbon and hydrogen. The balance of the carbon-containing filmmay have an atomic concentration less than 0.5%, less than 0.1% or lessthan 0.01% of any element other than carbon or other than carbon andhydrogen according to embodiments.

Carbon hardmasks may be doped to increase etch selectivity, though thisis optional for the etch processes presented herein since theselectivity is already high without doping. For the sake ofcompleteness, carbon hardmasks may be formed from carbon-containingmaterial which further comprises one of sulfur, boron or phosphorus.

The selectivity of etch processes 100 and 200 (exposed carbon-containingmaterial:exposed silicon) may be greater than or about 25:1, greaterthan or about 50:1 or greater than or about 75:1 in embodiments. Theexposed portion of silicon has an exposed surface having no native oxideor silicon oxide on the exposed surface in embodiments. The selectivityof etch processes 100 and 200 (exposed carbon-containingmaterial:exposed silicon oxide) may be greater than or about 25:1,greater than or about 50:1 or greater than or about 75:1 according toembodiments. The selectivity of etch processes 100 and 200 (exposedcarbon-containing material:exposed silicon nitride) may be greater thanor about 25:1, greater than or about 50:1 or greater than or about 75:1in embodiments. The selectivity of etch processes 100 and 200 (exposedcarbon-containing material:exposed silicon carbide) may be greater thanor about 25:1, greater than or about 50:1 or greater than or about 75:1according to embodiments. The selectivity of etch processes 100 and 200(exposed carbon-containing material:exposed silicon carbon nitride) maybe greater than or about 25:1, greater than or about 50:1 or greaterthan or about 75:1 in embodiments. No silicon carbide, silicon carbonnitride, silicon oxide, silicon or silicon nitride were etched usingetch processes 100 and 200 according to embodiments.

In all processes described herein the remote plasma region may be devoidof hydrogen, in embodiments, during the excitation of the remote plasma.For example, the remote plasma region may be devoid of ammonia duringexcitation of the remote plasma. A hydrogen source (e.g. ammonia) mayinteract with the fluorine-containing precursor in the plasma to formprecursors which remove silicon oxide by forming solid residueby-products on the silicon oxide surface. This reaction reduces theselectivity of the exposed carbon-containing portions as compared withexposed silicon oxide portions.

The methods presented herein include applying power to thefluorine-containing precursor and the oxygen-containing precursor in theremote plasma region to generate the plasma effluents. As would beappreciated by one of ordinary skill in the art, the plasma may includea number of charged and neutral species including radicals and ions. Theplasma may be generated using known techniques (e.g., RF, capacitivelycoupled, inductively coupled). In embodiments, the remote plasma poweris applied to the remote plasma region at a level between 5 W and 5 kWor between 25 W and 500 W. The remote plasma power may be applied usinginductive coils, in embodiments, in which case the remote plasma will bereferred to as an inductively-coupled plasma (ICP). The remote plasmapower may be a capacitively-coupled plasma in embodiments.

In embodiments, an ion suppressor as described in the exemplaryequipment section may be used to provide radical and/or neutral speciesfor selectively etching carbon-containing films. The ion suppressor mayalso be referred to as an ion suppression element. In embodiments, forexample, the ion suppressor is used to filter etching plasma effluents(including radical-fluorine) to selectively etch a carbon-containingfilm. The ion suppressor may be included in each exemplary processdescribed herein. Using the plasma effluents, an etch rate selectivityof carbon-containing material relative to silicon, silicon oxide andsilicon nitride may be achieved.

The ion suppressor may be used to provide a reactive gas having a higherconcentration of radicals than ions. Plasma effluents pass through theion suppressor disposed between the remote plasma region and thesubstrate processing region. The ion suppressor functions todramatically reduce or substantially eliminate ionically charged speciestraveling from the plasma generation region to the substrate. Theelectron temperature may be measured using a Langmuir probe in thesubstrate processing region during excitation of a plasma in the remoteplasma region on the other side of the ion suppressor. In embodiments,the electron temperature may be less than 0.5 eV, less than 0.45 eV,less than 0.4 eV, or less than 0.35 eV. These extremely low values forthe electron temperature are enabled by the presence of the showerheadand/or the ion suppressor positioned between the substrate processingregion and the remote plasma region. Uncharged neutral and radicalspecies may pass through the openings in the ion suppressor to react atthe substrate. Because most of the charged particles of a plasma arefiltered or removed by the ion suppressor, the substrate is notnecessarily biased during the etch process. Such a process usingradicals and other neutral species can reduce plasma damage compared toconventional plasma etch processes that include sputtering andbombardment. The ion suppressor helps control the concentration of ionicspecies in the reaction region at a level that assists the process.Embodiments of the present invention are also advantageous overconventional wet etch processes where surface tension of liquids cancause bending and peeling of small features.

Alternatively, the substrate processing region may be described hereinas “plasma-free” during the etch processes described herein.“Plasma-free” does not necessarily mean the region is devoid of plasma.Ionized species and free electrons created within the plasma region maytravel through pores (apertures) in the partition (showerhead) atexceedingly small concentrations. The borders of the plasma in thechamber plasma region are hard to define and may encroach upon thesubstrate processing region through the apertures in the showerhead.Furthermore, a low intensity plasma may be created in the substrateprocessing region without eliminating desirable features of the etchprocesses described herein. All causes for a plasma having much lowerintensity ion density than the chamber plasma region during the creationof the excited plasma effluents do not deviate from the scope of“plasma-free” as used herein.

Additional process parameters are disclosed in the course of describingan exemplary processing chamber and system.

Exemplary Processing System

Processing chambers that may implement embodiments of the presentinvention may be included within processing platforms such as theFRONTIER system, available from Applied Materials, Inc. of Santa Clara,Calif.

FIG. 3 shows a top plan view of one embodiment of a processing tool 1000of deposition, etching, baking, and curing chambers according todisclosed embodiments. In the figure, a pair of front opening unifiedpods (FOUPs) 1002 supply substrates of a variety of sizes that arereceived by robotic arms 1004 and placed into a low pressure holdingarea 1006 before being placed into one of the substrate processingchambers 1008 a-f, positioned in tandem sections 1009 a-c. A secondrobotic arm 1010 may be used to transport the substrate wafers from theholding area 106 to the substrate processing chambers 1008 a-f and back.Each substrate processing chamber 1008 a-f, can be outfitted to performa number of substrate processing operations including the dry etchprocesses described herein in addition to cyclical layer deposition(CLD), atomic layer deposition (ALD), chemical vapor deposition (CVD),physical vapor deposition (PVD), etch, pre-clean, degas, orientation,and other substrate processes.

The substrate processing chambers 1008 a-f may include one or moresystem components for depositing, annealing, curing and/or etching afilm on the substrate wafer. In one configuration, two pairs of theprocessing chamber, e.g., 1008 c-d and 1008 e-f, may be used to depositmaterial on the substrate, and the third pair of processing chambers,e.g., 1008 a-b, may be used to etch the deposited film. In anotherconfiguration, all three pairs of chambers, e.g., 1008 a-f, may beconfigured to etch a film on the substrate. Any one or more of theprocesses described may be carried out in chamber(s) separated from thefabrication system shown in disclosed embodiments. It will beappreciated that additional configurations of deposition, etching,annealing, and curing chambers for films are contemplated by system1000.

FIG. 4A shows a cross-sectional view of an exemplary process chambersection 2000 with partitioned plasma generation regions within theprocessing chamber. During film etching, e.g., silicon, polysilicon,silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide,carbon-containing material, etc., a process gas may be flowed into thefirst plasma region 2015 through a gas inlet assembly 2005. A remoteplasma system (RPS) unit 2001 may be included in the system, and mayprocess a gas which then may travel through gas inlet assembly 2005. Theinlet assembly 2005 may include two or more distinct gas supply channelswhere the second channel (not shown) may bypass the RPS unit 2001.Accordingly, in disclosed embodiments the precursor gases may bedelivered to the processing chamber in an unexcited state. In anotherexample, the first channel provided through the RPS may be used for theprocess gas and the second channel bypassing the RPS may be used for atreatment gas in disclosed embodiments. The process gases may be excitedwithin the RPS unit 2001 prior to entering the first plasma region 2015.Accordingly, a fluorine-containing precursor, for example, may passthrough RPS 2001 or bypass the RPS unit in disclosed embodiments.Various other examples encompassed by this arrangement will be similarlyunderstood.

A cooling plate 2003, faceplate 2017, ion suppressor 2023, showerhead2025, and a substrate support 2065, having a substrate 2055 disposedthereon, are shown and may each be included according to disclosedembodiments. The pedestal 2065 may have a heat exchange channel throughwhich a heat exchange fluid flows to control the temperature of thesubstrate. This configuration may allow the substrate 2055 temperatureto be cooled or heated to maintain relatively low temperatures, such asbetween about −20° C. to about 200° C., or there between. The heatexchange fluid may comprise ethylene glycol and/or water. The wafersupport platter of the pedestal 2065, which may comprise aluminum,ceramic, or a combination thereof, may also be resistively heated inorder to achieve relatively high temperatures, such as from up to orabout 100° C. to above or about 1100° C., using an embedded resistiveheater element. The heating element may be formed within the pedestal asone or more loops, and an outer portion of the heater element may runadjacent to a perimeter of the support platter, while an inner portionruns on the path of a concentric circle having a smaller radius. Thewiring to the heater element may pass through the stem of the pedestal2065, which may be further configured to rotate.

The faceplate 2017 may be pyramidal, conical, or of another similarstructure with a narrow top portion expanding to a wide bottom portion.The faceplate 2017 may additionally be flat as shown and include aplurality of through-channels used to distribute process gases. Plasmagenerating gases and/or plasma excited species, depending on use of theRPS 2001, may pass through a plurality of holes in faceplate 2017 for amore uniform delivery into the first plasma region 2015.

Exemplary configurations may include having the gas inlet assembly 2005open into a gas supply region 2058 partitioned from the first plasmaregion 2015 by faceplate 2017 so that the gases/species flow through theholes in the faceplate 2017 into the first plasma region 2015.Structural and operational features may be selected to preventsignificant backflow of plasma from the first plasma region 2015 backinto the supply region 2058, gas inlet assembly 2005, and fluid supplysystem (not shown). The structural features may include the selection ofdimensions and cross-sectional geometries of the apertures in faceplate2017 to deactivate back-streaming plasma. The operational features mayinclude maintaining a pressure difference between the gas supply region2058 and first plasma region 2015 that maintains a unidirectional flowof plasma through the showerhead 2025. The faceplate 2017, or aconductive top portion of the chamber, and showerhead 2025 are shownwith an insulating ring 2020 located between the features, which allowsan AC potential to be applied to the faceplate 2017 relative toshowerhead 2025 and/or ion suppressor 2023. The insulating ring 2020 maybe positioned between the faceplate 2017 and the showerhead 2025 and/orion suppressor 2023 enabling a capacitively coupled plasma (CCP) to beformed in the first plasma region. A baffle (not shown) may additionallybe located in the first plasma region 2015, or otherwise coupled withgas inlet assembly 2005, to affect the flow of fluid into the regionthrough gas inlet assembly 2005.

The ion suppressor 2023 may comprise a plate or other geometry thatdefines a plurality of apertures throughout the structure that areconfigured to suppress the migration of charged species (e.g., ions) outof the plasma excitation region 2015 while allowing uncharged neutral orradical species to pass through the ion suppressor 2023 into anactivated gas delivery region between the suppressor and the showerhead.In disclosed embodiments, the ion suppressor 2023 may comprise aperforated plate with a variety of aperture configurations. Theseuncharged species may include highly reactive species that aretransported with less reactive carrier gas through the apertures. Asnoted above, the migration of ionic species through the holes may bereduced, and in some instances completely suppressed. Controlling theamount of ionic species passing through the ion suppressor 2023 mayprovide increased control over the gas mixture brought into contact withthe underlying wafer substrate, which in turn may increase control ofthe deposition and/or etch characteristics of the gas mixture. Forexample, adjustments in the ion concentration of the gas mixture cansignificantly alter its etch selectivity. In alternative embodiments inwhich deposition is performed, it can also shift the balance ofconformal-to-flowable style depositions for dielectric materials,carbon-containing materials, and other materials.

The plurality of holes in the ion suppressor 2023 may be configured tocontrol the passage of the activated gas, i.e., the ionic, radical,and/or neutral species, through the ion suppressor 2023. For example,the aspect ratio of the holes, or the hole diameter to length, and/orthe geometry of the holes may be controlled so that the flow ofionically-charged species in the activated gas passing through the ionsuppressor 2023 is reduced. The holes in the ion suppressor 2023 mayinclude a tapered portion that faces the plasma excitation region 2015,and a cylindrical portion that faces the showerhead 2025. Thecylindrical portion may be shaped and dimensioned to control the flow ofionic species passing to the showerhead 2025. An adjustable electricalbias may also be applied to the ion suppressor 2023 as an additionalmeans to control the flow of ionic species through the suppressor.

The ion suppression element 2023 may function to reduce or eliminate theamount of ionically-charged species traveling from the plasma generationregion to the substrate. Uncharged neutral and radical species may stillpass through the openings in the ion suppressor to react with thesubstrate. Showerhead 2025 in combination with ion suppressor 2023 mayallow a plasma present in chamber plasma region 2015 to avoid directlyexciting gases in substrate processing region 2033, while still allowingexcited species to travel from chamber plasma region 2015 into substrateprocessing region 2033. In this way, the chamber may be configured toprevent the plasma from contacting a substrate 2055 being etched. Thismay advantageously protect a variety of intricate structures and filmspatterned on the substrate, which may be damaged, dislocated, orotherwise warped if directly contacted by a generated plasma.Additionally, when plasma is allowed to contact the underlying materialexposed by trenches, such as the etch stop, the rate at which theunderlying material etches may increase.

The processing system may further include a power supply 2040electrically coupled with the processing chamber to provide electricpower to the faceplate 2017, ion suppressor 2023, showerhead 2025,and/or pedestal 2065 to generate a plasma in the first plasma region2015 or processing region 2033. The power supply may be configured todeliver an adjustable amount of power to the chamber depending on theprocess performed. Such a configuration may allow for a tunable plasmato be used in the processes being performed. Unlike a remote plasmaunit, which is often presented with on or off functionality, a tunableplasma may be configured to deliver a specific amount of power to theplasma region 2015. This in turn may allow development of particularplasma characteristics such that precursors may be dissociated inspecific ways to enhance the etching profiles produced by theseprecursors.

A plasma may be ignited either in chamber plasma region 2015 aboveshowerhead 2025 or substrate processing region 2033 below showerhead2025. A plasma may be present in chamber plasma region 2015 to produceradical-fluorine precursors from an inflow of a fluorine-containingprecursor. An AC voltage typically in the radio frequency (RF) range maybe applied between the conductive top portion of the processing chamber,such as faceplate 2017, and showerhead 2025 and/or ion suppressor 2023to ignite a plasma in chamber plasma region 2015 during deposition. AnRF power supply may generate a high RF frequency of 13.56 MHz but mayalso generate other frequencies alone or in combination with the 13.56MHz frequency.

Plasma power can be of a variety of frequencies or a combination ofmultiple frequencies. In the exemplary processing system the plasma maybe provided by RF power delivered to faceplate 2017 relative to ionsuppressor 2023 and/or showerhead 2025. The RF power may be betweenabout 10 watts and about 2000 watts, between about 100 watts and about2000 watts, between about 200 watts and about 1500 watts, or betweenabout 200 watts and about 1000 watts in different embodiments. The RFfrequency applied in the exemplary processing system may be low RFfrequencies less than about 200 kHz, high RF frequencies between about10 MHz and about 15 MHz, or microwave frequencies greater than or about1 GHz in different embodiments. The plasma power may becapacitively-coupled (CCP) or inductively-coupled (ICP) into the remoteplasma region.

The top plasma region 2015 may be left at low or no power when a bottomplasma in the substrate processing region 2033 is turned on to, forexample, cure a film or clean the interior surfaces bordering substrateprocessing region 2033. A plasma in substrate processing region 2033 maybe ignited by applying an AC voltage between showerhead 2055 and thepedestal 2065 or bottom of the chamber. A cleaning gas may be introducedinto substrate processing region 2033 while the plasma is present.

A fluid, such as a precursor, for example a fluorine-containingprecursor, may be flowed into the processing region 2033 by embodimentsof the showerhead described herein. Excited species derived from theprocess gas in the plasma region 2015 may travel through apertures inthe ion suppressor 2023, and/or showerhead 2025 and react with anadditional precursor flowing into the processing region 2033 from aseparate portion of the showerhead. Alternatively, if all precursorspecies are being excited in plasma region 2015, no additionalprecursors may be flowed through the separate portion of the showerhead.Little or no plasma may be present in the processing region 2033according to embodiments. Excited derivatives of the precursors maycombine in the region above the substrate and, on occasion, on thesubstrate to etch structures or remove species on the substrate indisclosed applications.

Exciting the fluids in the first plasma region 2015 directly, orexciting the fluids in the RPS unit 2001, may provide several benefits.The concentration of the excited species derived from the fluids may beincreased within the processing region 2033 due to the plasma in thefirst plasma region 2015. This increase may result from the location ofthe plasma in the first plasma region 2015. The processing region 2033may be located closer to the first plasma region 2015 than the remoteplasma system (RPS) 2001, leaving less time for the excited species toleave excited states through collisions with other gas molecules, wallsof the chamber, and surfaces of the showerhead.

The uniformity of the concentration of the excited species derived fromthe process gas may also be increased within the processing region 2033.This may result from the shape of the first plasma region 2015, whichmay be more similar to the shape of the processing region 2033. Excitedspecies created in the RPS unit 2001 may travel greater distances inorder to pass through apertures near the edges of the showerhead 2025relative to species that pass through apertures near the center of theshowerhead 2025. The greater distance may result in a reduced excitationof the excited species and, for example, may result in a slower growthrate near the edge of a substrate. Exciting the fluids in the firstplasma region 2015 may mitigate this variation for the fluid flowedthrough RPS 2001.

The processing gases may be excited in the RPS unit 2001 and may bepassed through the showerhead 2025 to the processing region 2033 in theexcited state. Alternatively, power may be applied to the firstprocessing region to either excite a plasma gas or enhance an alreadyexcited process gas from the RPS. While a plasma may be generated in theprocessing region 2033, a plasma may alternatively not be generated inthe processing region. In one example, the only excitation of theprocessing gas or precursors may be from exciting the processing gasesin the RPS unit 2001 to react with the substrate 2055 in the processingregion 2033.

In addition to the fluid precursors, there may be other gases introducedat varied times for varied purposes, including carrier gases to aiddelivery. A treatment gas may be introduced to remove unwanted speciesfrom the chamber walls, the substrate, the deposited film and/or thefilm during deposition. A treatment gas may be excited in a plasma andthen used to reduce or remove residual content inside the chamber. Inother disclosed embodiments the treatment gas may be used without aplasma. When the treatment gas includes water vapor, the delivery may beachieved using a mass flow meter (MFM), mass flow controller (MFC), aninjection valve, or by commercially available water vapor generators.The treatment gas may be introduced to the processing region 2033,either through the RPS unit or bypassing the RPS units, and may furtherbe excited in the first plasma region.

FIG. 4B shows a detailed view of the features affecting the processinggas distribution through faceplate 2017. As shown in FIGS. 4A and 4B,faceplate 2017, cooling plate 2003, and gas inlet assembly 2005intersect to define a gas supply region 2058 into which process gasesmay be delivered from gas inlet 2005. The gases may fill the gas supplyregion 2058 and flow to first plasma region 2015 through apertures 2059in faceplate 2017. The apertures 2059 may be configured to direct flowin a substantially unidirectional manner such that process gases mayflow into processing region 2033, but may be partially or fullyprevented from backflow into the gas supply region 2058 after traversingthe faceplate 2017.

The gas distribution assemblies such as showerhead 2025 for use in theprocessing chamber section 2000 may be referred to as dual channelshowerheads (DCSH) and are additionally detailed in the embodimentsdescribed in FIGS. 4A-4B as well as FIG. 5 herein. The dual channelshowerhead may provide for etching processes that allow for separationof etchants outside of the processing region 2033 to provide limitedinteraction with chamber components and each other prior to beingdelivered into the processing region.

The showerhead 2025 may comprise an upper plate 2014 and a lower plate2016. The plates may be coupled with one another to define a volume 2018between the plates. The coupling of the plates may be so as to providefirst fluid channels 2019 through the upper and lower plates, and secondfluid channels 2021 through the lower plate 2016. The formed channelsmay be configured to provide fluid access from the volume 2018 throughthe lower plate 2016 via second fluid channels 2021 alone, and the firstfluid channels 2019 may be fluidly isolated from the volume 2018 betweenthe plates and the second fluid channels 2021. The volume 2018 may befluidly accessible through a side of the gas distribution assembly 2025.Although the exemplary system of FIG. 4A includes a dual-channelshowerhead, it is understood that alternative distribution assembliesmay be utilized that maintain first and second precursors fluidlyisolated prior to the processing region 2033. For example, a perforatedplate and tubes underneath the plate may be utilized, although otherconfigurations may operate with reduced efficiency or not provide asuniform processing as the dual-channel showerhead as described.

In the embodiment shown, showerhead 2025 may distribute via first fluidchannels 2019 process gases which contain plasma effluents uponexcitation by a plasma in chamber plasma region 2015 or from RPS unit2001. In embodiments, the process gas introduced into the RPS unit 2001and/or chamber plasma region 2015 may contain fluorine, e.g., CF₄, NF₃,or XeF₂, oxygen, e.g. N₂O, or hydrogen-containing precursors, e.g. H₂ orNH₃. One or both process gases may also include a carrier gas such ashelium, argon, nitrogen (N₂), etc. Plasma effluents may include ionizedor neutral derivatives of the process gas and may also be referred toherein as a radical-fluorine precursor, referring to the atomicconstituent of the process gas introduced. In an example, afluorine-containing gas, such as NF₃, may be excited in the RPS unit2001 and passed through regions 2015 and 2033 without the additionalgeneration of plasmas in those regions. Plasma effluents from the RPSunit 2001 may pass through the showerhead 2025 and then react with thesubstrate 2055. After passing through the showerhead 2025, plasmaeffluents may include radical species and may be essentially devoid ofionic species or UV light. These plasma effluents may react with filmson the substrate 2055, e.g., titanium nitride and other maskingmaterial.

The gas distribution assemblies 2025 for use in the processing chambersection 2000 are referred to as dual channel showerheads (DCSH) and aredetailed in the embodiments described in FIG. 5 herein. The dual channelshowerhead may allow for flowable deposition of a material, andseparation of precursor and processing fluids during operation. Theshowerhead may alternatively be utilized for etching processes thatallow for separation of etchants outside of the reaction zone to providelimited interaction with chamber components and each other prior tobeing delivered into the processing region.

FIG. 5 is a bottom view of a showerhead 3025 for use with a processingchamber according to disclosed embodiments. Showerhead 3025 maycorrespond with the showerhead shown in FIG. 4A. Through-holes 3065,which show a view of first fluid channels 2019, may have a plurality ofshapes and configurations in order to control and affect the flow ofprecursors through the showerhead 3025. Small holes 3075, which show aview of second fluid channels 2021, may be distributed substantiallyevenly over the surface of the showerhead, even among the through-holes3065, which may help to provide more even mixing of the precursors asthey exit the showerhead than other configurations.

As used herein “substrate” may be a support substrate with or withoutlayers formed thereon. A patterned substrate may be an insulator or asemiconductor of a variety of doping concentrations and profiles andmay, for example, be a semiconductor substrate of the type used in themanufacture of integrated circuits. Exposed “silicon” of the patternedsubstrate is predominantly Si but may include minority concentrations ofother elemental constituents such as nitrogen, oxygen, hydrogen andcarbon. In embodiments, silicon consists of or essentially of silicon.Exposed “silicon nitride” of the patterned substrate is predominantlySiN but may include minority concentrations of other elementalconstituents such as oxygen, hydrogen and carbon. In embodiments,silicon carbide consists of or essentially of silicon and carbon.Exposed “silicon carbide” of the patterned substrate is predominantlySiC but may include minority concentrations of other elementalconstituents such as oxygen, hydrogen and nitrogen. In embodiments,silicon carbide consists of or essentially of silicon and carbon.Exposed “silicon carbon nitride” of the patterned substrate ispredominantly SiCN, but may include minority concentrations of otherelemental constituents such as oxygen and hydrogen. In embodiments,silicon carbon nitride consists of or essentially of silicon, carbon andnitrogen. Exposed “silicon oxide” of the patterned substrate ispredominantly SiO₂ but may include minority concentrations of otherelemental constituents such as nitrogen, hydrogen and carbon. Inembodiments, silicon oxide consists of or essentially of silicon andoxygen.

The term “precursor” is used to refer to any process gas which takespart in a reaction to either remove material from or deposit materialonto a surface. “Plasma effluents” describe gas exiting from the remoteplasma region (e.g. the chamber plasma region) and entering thesubstrate processing region. Plasma effluents are in an “excited state”wherein at least some of the gas molecules are in vibrationally-excited,dissociated and/or ionized states. A “radical precursor” is used todescribe plasma effluents (a gas in an excited state which is exiting aplasma) which participate in a reaction to either remove material fromor deposit material on a surface. “Radical-fluorine” is a radicalprecursor which contain fluorine but may contain other elementalconstituents. The phrase “inert gas” refers to any gas which does notform chemical bonds in the film during or after the etch process.Exemplary inert gases include noble gases but may include other gases solong as no chemical bonds are formed when (typically) trace amounts aretrapped in a film.

The terms “gap” and “trench” are used throughout with no implicationthat the etched geometry has a large horizontal aspect ratio. Viewedfrom above the surface, trenches may appear circular, oval, polygonal,rectangular, or a variety of other shapes. A trench may be in the shapeof a moat around an island of material. The term “via” is used to referto a low aspect ratio trench (as viewed from above) which may or may notbe filled with metal to form a vertical electrical connection. As usedherein, a conformal etch process refers to a generally uniform removalof material on a surface in the same shape as the surface, i.e., thesurface of the etched layer and the pre-etch surface are generallyparallel. A person having ordinary skill in the art will recognize thatthe etched interface likely cannot be 100% conformal and thus the term“generally” allows for acceptable tolerances.

In the preceding description, for the purposes of explanation, numerousdetails have been set forth in order to provide an understanding ofvarious embodiments of the present technology. It will be apparent toone skilled in the art, however, that certain embodiments may bepracticed without some of these details, or with additional details.

Having disclosed several embodiments, it will be recognized by those ofskill in the art that various modifications, alternative constructions,and equivalents may be used without departing from the spirit of theembodiments. Additionally, a number of well-known processes and elementshave not been described in order to avoid unnecessarily obscuring thepresent technology. Accordingly, the above description should not betaken as limiting the scope of the technology.

Where a range of values is provided, it is understood that eachintervening value, to the smallest fraction of the unit of the lowerlimit, unless the context clearly dictates otherwise, between the upperand lower limits of that range is also specifically disclosed. Anynarrower range between any stated values or unstated intervening valuesin a stated range and any other stated or intervening value in thatstated range is encompassed. The upper and lower limits of those smallerranges may independently be included or excluded in the range, and eachrange where either, neither, or both limits are included in the smallerranges is also encompassed within the technology, subject to anyspecifically excluded limit in the stated range. Where the stated rangeincludes one or both of the limits, ranges excluding either or both ofthose included limits are also included.

As used herein and in the appended claims, the singular forms “a”, “an”,and “the” include plural references unless the context clearly dictatesotherwise. Thus, for example, reference to “a trench” includes aplurality of such trenches, and reference to “the layer” includesreference to one or more layers and equivalents thereof known to thoseskilled in the art, and so forth.

Also, the words “comprise(s)”, “comprising”, “contain(s)”, “containing”,“include(s)”, and “including”, when used in this specification and inthe following claims, are intended to specify the presence of statedfeatures, integers, components, or operations, but they do not precludethe presence or addition of one or more other features, integers,components, operations, acts, or groups.

The invention claimed is:
 1. A method of etching a patterned substrate,the method comprising: transferring the patterned substrate into asubstrate processing region of a substrate processing chamber, whereinthe patterned substrate has exposed portions of carbon-containingmaterial and an exposed alternative material, wherein thecarbon-containing material is silicon-free and wherein the exposedalternative material consists of one of exposed silicon, exposed siliconnitride, exposed silicon carbon nitride, exposed silicon carbide orexposed silicon oxide; flowing an oxygen-containing precursor into aremote plasma region fluidly coupled to the substrate processing region;flowing a fluorine-containing precursor into the remote plasma region;combining the oxygen-containing precursor with the fluorine-containingprecursor; forming a remote plasma in the remote plasma region from theoxygen-containing precursor and the fluorine-containing precursor toproduce plasma effluents; passing the plasma effluents through an ionsuppressor and subsequently into the substrate processing region; andetching the exposed portions of carbon-containing material, wherein thesubstrate processing region is devoid of ionic species during theetching.
 2. The method of claim 1 wherein the carbon-containing materialconsists of carbon.
 3. The method of claim 1 wherein thecarbon-containing material consists of carbon and hydrogen.
 4. Themethod of claim 1 wherein the operation of forming the remote plasmacomprises a remote plasma power between 25 W and 500 W.
 5. The method ofclaim 1 wherein a pressure in the substrate processing region is betweenabout 0.1 Torr and about 15 Torr during the operation of etching theexposed portions of carbon-containing material.
 6. The method of claim 1wherein an electron temperature in the substrate processing region isless than 0.5 eV during the operation of etching the exposed portions ofcarbon-containing material.
 7. The method of claim 1 wherein thefluorine-containing precursor comprises NF₃.
 8. The method of claim 1wherein the fluorine-containing precursor comprises a precursor selectedfrom the group consisting of hydrogen fluoride, atomic fluorine,diatomic fluorine, carbon tetrafluoride and xenon difluoride.
 9. Amethod of etching a patterned substrate, the method comprising:transferring the patterned substrate into a substrate processing regionof a substrate processing chamber, wherein the patterned substrate hasexposed carbon hardmask, wherein the exposed carbon hardmask consistsonly of carbon and hydrogen and wherein the patterned substrate furthercomprises a second exposed portion comprising one of silicon, siliconnitride, silicon carbide, silicon carbon nitride or silicon oxide;flowing a fluorine-containing precursor and an oxygen-containingprecursor into a remote plasma region fluidly coupled to the substrateprocessing region while forming a remote plasma in the remote plasmaregion to produce plasma effluents; flowing the plasma effluents in thesubstrate processing region, and etching the exposed carbon hardmask,wherein the substrate processing region is devoid of ionic speciesduring the operation of etching the exposed carbon hardmask and whereina selectivity of the etching (exposed carbon hardmask:second exposedportion) is greater than 25:1.
 10. The method of claim 9 wherein atemperature of the patterned substrate is between about −5° C. and about40° C. during the operation of etching the exposed carbon hardmask. 11.The method of claim 9 wherein the oxygen-containing precursor is one ofoxygen (O₂), ozone (O₃), nitrogen dioxide or nitrous oxide.
 12. Themethod of claim 9 wherein plasma effluents pass through an ionsuppressor disposed between the remote plasma region and the substrateprocessing region.
 13. The method of claim 9 wherein thecarbon-containing material further comprises one of boron, phosphorus orsulfur.
 14. A method of etching a patterned substrate, the methodcomprising: transferring the patterned substrate into a substrateprocessing region of a substrate processing chamber, wherein thepatterned substrate has exposed portions of carbon hardmask; flowingnitrogen trifluoride into a remote plasma region and combining oxygenwith the nitrogen trifluoride, wherein the remote plasma region isfluidly coupled to the substrate processing region; forming a remoteplasma from the nitrogen trifluoride and the oxygen in the remote plasmaregion to produce plasma effluents; passing the plasma effluents througha showerhead disposed between the remote plasma region and the substrateprocessing region; etching the exposed portions of carbon hardmask,wherein the carbon hardmask is silicon-free and the substrate processingregion is devoid of plasma during the etching; and removing thepatterned substrate from the substrate processing region.